1. Field of the Invention
This invention relates to a tire uniformity machine which serves to inspect accuracy in uniformity of various tires, and more particularly to an apparatus for automatically adjusting the rim width, namely, the width of the space between upper and lower rims which detachably grip therebetween a tire to be tested on a tire uniformity machine.
2. Description of the Prior Art
Generally, as exemplified in FIG. 8, a tire uniformity machine of this sort is arranged to grip a testing tire T releasably between upper and lower rims TR and BR for rotation about its axis and to bring the rotating tire T into contact with a load wheel LW which serves as a substitute road surface, inspecting the accuracy in uniformity of the tire T through upper and lower load cells LC-T and LC-B. The width of the interval between the upper and lower rims TR and BR needs to be adjusted according to the size of the testing tire T to be loaded on the machine.
In this regard, there has been known in the art a rim width adjusting mechanism as exemplified in FIG. 9 (Japanese Utility Model Publication 62-2520).
In FIG. 9, indicated at 51 is an upper spindle which is rotatably supported on a machine frame 52 through bearings. An upper rim 54 is replaceably mounted on the lower end of the upper spindle 51 through a hub 53. Provided opposingly to and in vertical alignment with the upper spindle 51 is a lower spindle 55 which is movable in the axial direction and at the same time rotatable about its axis. A lower rim 56 is coaxially mounted on the upper end of the lower spindle 55. Further, a chuck male adapter 58 is provided centrally on the upper end of the lower spindle 55, the chuck male adapter 58 having a male taper portion 57 in coaxial relation with the lower spindle 55. The afore-mentioned hub 53 is provided with a taper hole 59 centrally on its lower side in concentric relation with the upper spindle 51, for fitting engagement with the male taper portion 57 of the chuck male adapter 58.
The width of the interval between the upper and lower rims can be altered by replacing the chuck male adapter 58 by a spare adapter of the height corresponding to the type and size of the tire T to be tested.
Namely, in case of the above-described prior art apparatus, the operator is required to replace the chuck male adapter manually every time when changing the tire size, stopping the operation of the uniformity machine for a long period of time despite deteriorations in efficiency. Besides, there have to be provided a large number of spare chuck male adapters 58 to cover the whole range of the rim width which is normally varied at a step of 0.5 inch, requiring a large space and a lot of efforts for storage.